• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4560-4570
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• 2022

Dynamic fault tree (DFT) and its related research methods have received extensive attention in safety analysis and reliability engineering. DFT can perform reliability modelling for systems with sequential correlation, resource sharing, and cold and hot spare parts. A technical modelling method of DFT is proposed for modelling ship collision accidents and loss-of-coolant accidents (LOCAs). Qualitative and quantitative analyses of DFT were carried out using the cutting sequence (CS)/extended cutting sequence (ECS) method. The results show nine types of dynamic fault failure modes in ship collision accidents, describing the fault propagation process of a dynamic system and reflect the dynamic changes of the entire accident system. The probability of a ship collision accident is 2.378 × 10^-9 by using CS. This failure mode cannot be expressed by a combination of basic events within the same event frame after an LOCA occurs in a marine nuclear reactor because the system contains warm spare parts. Therefore, the probability of losing reactor control was calculated as 8.125 × 10^-6 using the ECS. Compared with CS, ECS is more efficient considering expression and processing capabilities, and has a significant advantage considering cost.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1379-1384
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• 2017

To guarantee safety and reliability, RAMS(Reliability Availability Maintainability and Safety) activity for a communication software in train communication network is studied. In this paper, preliminary hazard analysis in RAMS activities is studied for the communication software. Preliminary hazard analysis is done through library for communication software that the specification is defined by IEC 61375. The hazards are defined, then causes and consequence for each hazard are defined. The total 36 preliminary hazards are classified. For high severity hazards are changed to acceptable level by upgrading of system requirement specification.

• Journal of the Korea Safety Management & Science
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• v.7 no.3
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• pp.47-61
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• 2005

Many researchers have proved that risk measurement of information systems is a very effective tool for improving confidence of information systems. However, information system risk in Korea still includes many subjective judgements. This study deals with applying a quantitative model to improve risk measurement of information system quality. First of all, we have come up with solutions to improve the evaluation efficiency on risk measurement. We have merged the risk guidelines of COBIT and CMM, and developed a quantified evaluation scheme that call by risk point. We have proved the validity of this model by interviews with experts and by case studies.

• Journal of the Korea Safety Management & Science
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• v.3 no.2
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• pp.145-154
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• 2001

This paper deals with Activity Analysis Method that is important procedure in Activity Based Costing System Implementation. There are many existing Activity Analysis Method, for example Interview, Questionnaire, Specialist Discussion and Work Measurement. Activity Analysis Data gained through this method has high reliability but this method bring about high cost. In case that certain company needs a strategic costing system, Activity Analysis Method which has high reliability will be need. But, if companies want the costing system as a internal decision making tool only, they need to design the ABC system fast and cheaply. This paper explains that Activity Analysis using existing finn material is good alternatives. So, this paper show the feasibility of Activity Analysis using existing firm material with comparing between job description, job specification information and Activity Analysis information.

• Journal of Auto-vehicle Safety Association
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• v.16 no.1
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• pp.49-54
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• 2024

This paper provides an analysis of the experimental procedures and results to ensure the reliability of the system manufactured for testing the hydrogen permeability of a 175 L compressed hydrogen container for a hydrogen bus. Based on the hydrogen permeability standard of 6 cc/(h·L), it was injected into the permeability test chamber at 10% intervals, and the permeated hydrogen concentration according to the injected amount was measured and compared with the actual amount of hydrogen permeated. As a result of the experiment, the measured value represented 96.34% of the actual permeation amount, which can be used as basic data for the hydrogen bus vessel permeability test system being built in Korea.

• Geomechanics and Engineering
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• v.36 no.2
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• pp.121-130
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• 2024

Many foundation projects are built on red-bed soft rocks, and the damage evolution of this kind of rocks affects the safety of these projects. At present, there is insufficient research on the damage evolution of red-bed soft rocks, especially the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation. Therefore, based on the dual-porosity characteristics of pores and fissures in soft rock, we adopted a cellular automata model to simulate the propagation of these voids in soft rocks under an external load. Further, we established a macro-mesoscopic damage model of red-bed soft rocks, and its reliability was verified by tests. The results indicate that the relationship between the number and voids size conformed to a quartic polynomial, whereas the relationship between the damage variable and damage porosity conformed to a logistic curve. The damage porosity was affected by dual-porosity parameters such as the fractal dimension of pores and fissures. We verified the reliability of the model by comparing the test results with an established damage model. Our research results described the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation and provided a theoretical basis for the damage evolution of these rocks.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.327-330
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• 2009

A Through-Bulkhead Initiation Module(TBIM) using CH-6 was designed. The TBIM works as the shock-wave generated by a donor charge transmits to the acceptor charge. The structural safety of TBIM housing was calculated via modeling analysis, and the ignition characteristic was proved by 10 cc closed bomb test(CBT). The reliability analysis was made using Probit method on the basis of CBT results. The optimal bulkhead thickness of TBIM which is the most important design parameter was determined using reliability analysis.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.145-157
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• 1989

본 논문의 주목적은 불연속 또는 연속계 구조물의 시스템 신뢰성해석(system reliability analysis)을 위한 보다 일반적인 방법을 소개하는데 있다. 본 논문에서는, 확대하중증분법(extended incremental load method)이라고 불리우는데, 지금까지의 신뢰성 해석법 중 종래의 하중증분법이 갖는 단점을 보완하고, 여러 형태의 하중이 작용하는 구조물에 대해, 부재의 파괴후 거동(post-ultimate behaviour)을 다른 방법보다 더 실제적으로 고려할 수 있는 장점을 갖도록 개발한 것이다. 본 방법의 또 하나의 장점은 구조설계시 사용하는 강도공식(strength formula) 을 시스템 신뢰성 해석에서 직접 이용할 수 있다는 점이다. 이 방법은 부유식 해양구조물 같은 연속계 구조물의 시스템 신뢰성 해석을 위해 개발되었는데, 이 논문에서는 실제 구조물은 다루지 않고, 방법의 정당성과 아울러 수정된 안전여유식의 적용가능성을 보여주는 것에 중점을 두었다. 본 논문의 부유식 해양구조물들에 적용한 결과는 후일 발표할 예정이다.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.66-82
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• 1999

The national long-term R&D program, updated in 1997, requires Korea Atomic Energy Research Institute(KAERI) to complete by the year 2006 the basic design of Korea Advanced Liquid Metal Reactor(KALIMER), along with supporting R&D work, with the capability of resolving the issue of spent fuel storage as well as with significantly enhanced safety. KALIMER is a 150 MWe pool-type sodium cooled prototype reactor that uses metallic fuel. The conceptual design is currently under way to establish a self-consistent design meeting a set of major safety design requirements for accident prevention. Some of the current emphasis includes those for inherent and passive means of negative reactivity insertion and decay heat removal, high shutdown reliability, prevention of and protection from sodium chemical reaction, and high seismic margin, among others. All of these requirements affect the reactor design significantly and involve extensive supporting R&D programs. This paper summarizes some of the results of conceptual engineering and design analyses performed for the safety of HAMMER in the area of inherent safety, passive decay heat removal, sodium water reaction, and seismic isolation.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.982-989
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• 2005

Safety of the Train Control System become more important along with the progress of the computer and the technology of communications in these days. Safety of the Train Traffic Control System needs an accurate analysis of the Hazard to reduce losses of a property and lives. Many of advanced railroad nations already had established safety standards when they set the system even considering scrap of railroad and put a great concern on developing safety system which is getting larger and more complicate. Domestic railroad system has to introduce improved technology and systematically prepare and make a scientific survey to achieve unparalleled reliability and safety as well. In this Study, ITCC CTC System will show the research and the analysis of the hazard to ensure the safety of software.